Thermostats are extensively used to control the circulation of coolant in internal combustion engines. Typically, thermostats include valves having a closed body containing a thermally expandable material, such as wax. A spring is provided to urge the valve to a closed position such that in the resting or cooled state the valve is normally closed. Hence, when the engine is first started, the valve is closed, allowing only a bypass circulation of coolant fluid between the engine and the thermostat, thereby enabling the engine to attain its optimum running temperature more quickly.
Once the engine temperature rises, the temperature of the bypass circulated fluid increases, causing the wax within the valve body to melt and expand, consequently thrusting out a piston. As a result, the thrusted out piston causes the displacement of the valve from the valve seat, allowing flow of coolant fluid from a radiator to the engine. As the engine temperature drops, the wax temperature falls, the valve closes, returning to bypass circulation only.
There is still an unmet need for a device which is capable of fine-tuning the opening and closing of the valve on demand, to enable lower and/or higher Start-to-Open (STO) temperature.